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Science : Acid test for intelligence

INTELLIGENCE may be influenced by pH levels in the brain, a team of
British researchers believes. This is the first time that intelligence has been
linked to a biochemical marker.

Caroline Rae of the MRC Biochemical and Clinical Magnetic Resonance
Spectroscopy Unit at the John Radcliffe Hospital, Oxford, and her colleagues
claim they have found a correlation between IQ and pH in the brain’s
cortex. A higher, or more alkaline, brain pH is more likely to be
associated with a higher IQ, they say.

Rae’s team measured pH levels in the brains of 42 boys aged between
6 and 13 using magnetic resonance spectroscopy (MRS), a noninvasive technique in
which the pH of the chemical environment—in this case the
brain—affects the ability of certain atomic nuclei to absorb energy in a
magnetic field. The boys also completed the Wechsler Intelligence Scale for
Children, one of the most widely used tests of IQ. It gives a score for
full-scale IQ, which combines scores for verbal and visuospatial skills. They
found a correlation of over 0.5 between IQ and brain pH (1 represents a
total correlation, 0 a random sample). Over a pH range of 6.99 to 7.09,
the boys’ IQs more than doubled, from 63 to 138.

Their findings, to be published in the Proceedings of the Royal Society
of London B (vol 1373, p 1061) on 22 August, do not suggest that the
acidity or alkalinity of brain cells directly determines IQ. They do, however,
suggest a link, and they beg the question of whether IQ could be artificially
manipulated by raising pH levels in the brain.

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Richard Lynn, emeritus professor of psychology, now retired from the
University of Ulster, Northern Ireland, says: “Several people have demonstrated
that the speed of transmission along the nerve fibres can be correlated with
intelligence. So if pH levels affect speed of transmission, then they
are probably going to affect intelligence.” He says there is evidence that
dietary supplements can result in increases in IQ—perhaps by altering
brain pH.

Other brain researchers are less convinced. “Although many aspects of
synaptic transmission are dependent on pH, or alter pH, nobody
has the slightest idea how these cellular variables relate to IQ,” says David
Attwell, a professor of physiology at University College London. The problem, he
says, is that a person’s brain pH fluctuates, even over the course of a
single day. It can be raised, for example, by hyperventilating. “A useful
follow-up to this study might be to measure IQ at different times in a single
subject while altering their brain pH with manipulations like
hyperventilation,” says Attwell.

Chris Brand, a psychologist at the University of Edinburgh whose book,
The g Factor, which links race with intelligence, was withdrawn from
publication earlier this year, has reservations about the findings. He points
out that on several parts of the Wechsler test the correlations between
pH and IQ are “worryingly diverse”. The correlation with scores for picture
arrangement, for example, was only 0.03. “That would make one critical of the
idea that what one was getting was a biochemical marker of IQ,” says Brand. He
says it may have been safer to confine the correlation to verbal IQ.